Add installation and usage instructions

[gonzalocasas]

After repeatedly being frustrated by the confusingly spread out installation instructions of this package, I propose we move them all from the wiki to here (which anyway has a much nicer formatting).

What I did is:

• Move the RAPID server side installation instructions that pertain to this branch, mostly verbatim copy (today I installed a new setup, and I did all the signals setup only to remember later on that the pull request to use those is not merged, so I purposely did not add that in this PR).
• Added the ROS package side of the installation (which currently is buried in the experimental package)
• Add bring up instructions (which shockingly enough, I could not find documented anywhere official)

I hope this makes sense and can be merged, even knowing that development is mostly switching to the new egm/rws stuff.

[gavanderhoorn]

This is not a bad idea, but four things:

1. please do add the signal setup info needed for Rebased and updated version of PR145 (robot_status msg publishing) #168 (was: Adds robot status publishing to Rapid driver #145) as that PR will be merged and then that information will be needed (or things won't work)
2. there are some markdown rendering issues (the comments about "restart the controller after you've made all changes" look like quotes right now fi)
3. please make the RobotStudio 6 menu locations and interface references the defaults (ie: switch them with the RS5 ones)
4. let's not add everything to the main readme: add a doc directory that contains three files named after the tutorials on the wiki: install_server.md, run_server.md and usage.md. That last one doesn't exist right now of course, but would include the "bringup" part that you added.

• Add bring up instructions (which shockingly enough, I could not find documented anywhere official)

thing is: you're viewing this repository and the packages in isolation. The idea was (and is) that this is part of a larger program, where the usage of driver components is supposed to be identical to others. Ideally there is no repetition of documentation, as they all work the same / similar enough. That is partly the reason why there are no "bringup instructions": users are supposed to either already know how to work with ros-i drivers or should refer to documentation on industrial_core (fi).

I'm not against adding it here though, but we should still have some structure.

[gavanderhoorn]

I'm going to close this here. Not because the contribution is not appreciated, but abb_driver is now hosted in its own repository.

The related issue has been transferred (see ros-industrial/abb_driver#1), but unfortunately GH does not support that for PRs.

ros-industrial/abb_driver#1 refers to this PR though, so the connection is retained.